1. Field of the Invention
The invention relates to a method for separating or cutting a flat pipe section of aluminum or an aluminum alloy from a solder-coated, thin-walled flat pipe section member, for example, an extruded flat pipe section member, in particular, a solder-coated thin-walled multi-chamber flat pipe section member, wherein by means of at least one sharp cutting blade a clean, bur-free separating cut is produced at a predetermined separating location. Such pipe sections are used in connection with heat exchangers. For producing different types of heat exchangers, the solder-coated flat pipe sections are connected by brazing to additional components.
2. Description of the Related Art
European patent 0 714 342 B1 discloses a method for separating an elongate thin-walled pipe into pipe sections. In this method, a notch is produced in the pipe material by means of a blade wherein the notch has a depth that is somewhat less than the thickness of the wall of the pipe. In a second step, the notch is widened and, subsequently, a tensile force is exerted causing the pipe section to become separated. In this way, a bur-free separation cut is obtained. However, this method has the disadvantage that, in the case of solder-coated section members to be separated into individual pipe sections, the cutting blades become worn very quickly. This is caused by the solder coating. Generally, aluminum silicon alloys having a high silicon contents or silicon alloys are used as a solder for the flat pipe sections of aluminum. The high contents of silicon makes this coating very hard and abrasive. The wear on the separating or cutting tools is significantly accelerated in comparison to pipes without coating. High tool expenditures are the result.
For an excellent separating cut, the precision cutting blade, also called cutter, must always be very sharp. A worn cutting edge results in jagged separating cuts, deformations, and bur formation; when jointing the sections in a subsequent brazing process, these flaws are detrimental and prevent, in the worst-case scenario, a tight or sealed solder connection. The worn separating tools must therefore be exchanged in a timely fashion for a new or re-sharpened tool. This exchange, including possibly an alignment, of the cutting tools in the separating device represents an expensive downtime. In order to prevent the fast wear of the cutting tools, it is possible to first separate the flat pipe section member, for example, the extruded section member, into flat pipe sections and to subsequently coat the individual sections with solder. However, handling of the individual sections is more complex and it is not possible to prevent that solder and flux agents reach the interior of the flat pipe sections during the solder coating process; this can lead to corrosion and solder erosion.